A voltage peak of a rectifier at a secondary-side of a direct current voltage conversion device is an important factor affecting the conversion efficiency and reliability of the direct current voltage conversion device. Energy of the voltage peak results mainly from energy of a parasitic capacitor(s) of the rectifier during charging, and a reverse recovery energy of the rectifier. Conventional clamp circuits used in a direct current voltage conversion device, such as RC damping (absorbing) circuits, and RCD damping (absorbing) circuit, are not able to clamp the voltage peak of the rectifier at a secondary-side to an ideal voltage value. Furthermore, such conventional clamp circuit is not highly reliable, resulting in the need to select a rectifier of a high voltage grade in order for the rectifier of a direct current voltage conversion device to endure voltages higher than the ideal voltage value. However, a rectifier of a high voltage grade may cost more, and may have a high turn-on resistance, which causes high power loss that decreases an overall conversion efficiency of the direct current voltage conversion device.